/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.flink.table.planner.functions.sql;

import org.apache.calcite.sql.SqlFunction;
import org.apache.calcite.sql.SqlFunctionCategory;
import org.apache.calcite.sql.SqlKind;
import org.apache.calcite.sql.SqlOperatorBinding;
import org.apache.calcite.sql.SqlSyntax;
import org.apache.calcite.sql.type.InferTypes;
import org.apache.calcite.sql.type.OperandTypes;
import org.apache.calcite.sql.type.ReturnTypes;
import org.apache.calcite.sql.type.SqlTypeFamily;
import org.apache.calcite.sql.type.SqlTypeName;
import org.apache.calcite.sql.type.SqlTypeTransforms;
import org.apache.calcite.sql.validate.SqlMonotonicity;

/**
 * Function that materializes a processing time attribute. After materialization the result can be
 * used in regular arithmetical calculations.
 */
public class ProctimeMaterializeSqlFunction extends SqlFunction {

    public ProctimeMaterializeSqlFunction() {
        super(
                "PROCTIME_MATERIALIZE",
                SqlKind.OTHER_FUNCTION,
                ReturnTypes.cascade(
                        ReturnTypes.explicit(SqlTypeName.TIMESTAMP, 3),
                        SqlTypeTransforms.TO_NULLABLE),
                InferTypes.RETURN_TYPE,
                OperandTypes.family(SqlTypeFamily.TIMESTAMP),
                SqlFunctionCategory.SYSTEM);
    }

    @Override
    public SqlSyntax getSyntax() {
        return SqlSyntax.FUNCTION;
    }

    @Override
    public SqlMonotonicity getMonotonicity(SqlOperatorBinding call) {
        return SqlMonotonicity.INCREASING;
    }

    @Override
    public boolean isDeterministic() {
        return false;
    }
}
